Is it possible to export as USD using python?
bpy.ops.wm.usd_export() operator

Blender 2.83 adds USD support but is still in beta so you won't find anything in the current API. However, there is a development version of the API called master which is mostly up to date. 

Highly recommend using blenders python console to figure out the operator call as well as all possible arguments:

&gt;&gt;&gt; bpy.ops.wm.usd_export(
                          filepath="", 
                          check_existing=True, 
                          filter_blender=False, 
                          filter_backup=False,
                          ....
                          )